mono/mini/mini-windows-tls-callback.c

   1 /**
   2  * Copyright 2019 Microsoft Corporation
   3  * Licensed under the MIT license. See LICENSE file in the project root for full license information.
   4  */
   5
   6 #include "mini-runtime.h"
   7
   8 #if defined(HOST_WIN32)
   9 #include "mini-windows.h"
  10 #include <windows.h>
  11
  12 /* Only reset by initial callback from OS loader with reason DLL_PROCESS_ATTACH */
  13 /* both for DLL and LIB callbacks, so no need to protect this variable. */
  14 static MonoWin32TLSCallbackType mono_win32_tls_callback_type = MONO_WIN32_TLS_CALLBACK_TYPE_NONE;
  15
  16 /* NOTE, this function needs to be in this source file to make sure linker */
  17 /* resolve this symbol from mini-windows.c, picking up callback and */
  18 /* included it in TLS Directory PE header. Function makes sure we only activate */
  19 /* one of the supported mono callback types at runtime (if multiple one has been used) */
  20 gboolean
  21 mono_win32_handle_tls_callback_type (MonoWin32TLSCallbackType callback_type)
  22 {
  23         /* Makes sure our tls callback doesn't get optimized away. */
  24         extern const PIMAGE_TLS_CALLBACK __mono_win32_tls_callback;
  25         const volatile PIMAGE_TLS_CALLBACK __tls_callback = __mono_win32_tls_callback;
  26
  27         if (mono_win32_tls_callback_type == MONO_WIN32_TLS_CALLBACK_TYPE_NONE)
  28                 mono_win32_tls_callback_type = callback_type;
  29
  30         if (callback_type != mono_win32_tls_callback_type)
  31                 return FALSE;
  32
  33         return TRUE;
  34 }
  35
  36 VOID NTAPI mono_win32_tls_callback (PVOID module_handle, DWORD reason, PVOID reserved);
  37
  38 VOID NTAPI mono_win32_tls_callback (PVOID module_handle, DWORD reason, PVOID reserved)
  39 {
  40         mono_win32_runtime_tls_callback ((HMODULE)module_handle, reason, reserved, MONO_WIN32_TLS_CALLBACK_TYPE_LIB);
  41 }
  42
  43 /* If we are building a static library that won't have access to DllMain we can't */
  44 /* correctly detach a thread before it terminates. The MSVC linker + runtime (also applies to MINGW) */
  45 /* uses a set of predefined segments/sections where callbacks can be stored and called */
  46 /* by OS loader (part of TLS Directory PE header), regardless if runtime is used */
  47 /* as a static or dynamic library. */
  48 #if (_MSC_VER >= 1400)
  49 #pragma const_seg (".CRT$XLX")
  50 extern const PIMAGE_TLS_CALLBACK __mono_win32_tls_callback = mono_win32_tls_callback;
  51 #pragma const_seg ()
  52 #elif defined(__MINGW64__) || (__MINGW32__)
  53 extern const PIMAGE_TLS_CALLBACK __mono_win32_tls_callback __attribute__ ((section (".CRT$XLX"))) = mono_win32_tls_callback;
  54 #else
  55 #pragma message ("TLS callback support not included in .CRT$XLX segment. Static linked runtime won't add callback into PE header.")
  56 #endif
  57 #endif